Unknown to them at the time another powerful nation had been consolidating it's power as well. The Neo Ottoman Empire had amassed from the remains of the Middle East, led by a man that was only referred to as The Prophet.
The Neo Ottoman Empire had its sights set on Eastern Europe as well, hoping to gain industry and agricultural land for it's growing population. Things turned sour immediately between the two European countries and the Neo Ottomans, with territory disputes and clashing of religious beliefs a major source of contention between the two sides.
Things devolved even further when the Emperor of the Holy Nation was assassinated while visiting a border town on the fringes of Holy Roman territory, with an extremest Ottoman group taking claim for the action.
Eventually border clashes between the two sides flared into full war with military operations all around the Eastern European theater.
With combat becoming more violent every day many countries around the world urged for peace. What happened however was a tragedy of catastrophic proportions.
The Neo Ottomans gave a final ultimatum after a squad of Arstadsenean assassin's infiltrated a Ottoman war council meeting and assassinated The Prophet himself along with many high ranking military officials. Arstadsen and the New Holy Roman Empire would bend a knee, or face atomic fire.
Thinking it was a bluff the cooperating Arstadsenean and Holy Roman armies forged through the scattered Ottoman military, making progress deep within Ottoman territory.
Being pushed to the brink the Ottoman Empire made good on its promise and launched it's stock of nuclear weapons. Arstadsen and the Roman Empire did the same, hoping to destroy some of the flying rockets in flight as well as destroy their enemy before more damage could be done.
While the majority of missiles we're indeed destroyed in transit many still hit the territories of both parties, causing unfathomable death all over the European and Middle Eastern territories, those that survived faced the radiation of not only the missiles that hit, but the missiles destroyed above them.
With most population centers destroyed, and radiation the highest it's been since the world had its first atomic catastrophe things quickly fell apart. The countries fractured and things became as bad as the wastelands that surrounded the once prosperous countries. With warlords and ex-government officials taking power in what remnants of the shattered civilizations they could.